Superstructure in self-advancing roof supports

ABSTRACT

THE INVENTION PROVIDES A SELF-ADVANCING ROOF SUPPORT PRIMARILY FOR MINE WORKINGS IN WHICH A ROOF-ENGAGING SUPERSTRUCTURE CARRIED BY A PLURALITY OF HYDRAULIC PROPS UPSTANDING FROM A BASE INCLUDES LATERALLY SPACED, LONGITUDINALLY EXTENDING, ROOF BARS CONNECTED WITH EACH OTHER BY TRANSVERSELY EXTENDING SPRING STRIP ELEMENTS INCORPORATING ONE OR MORE LOOPED, UNDULATING, OR ARCUATE PORTIONS TO PROVIDE AN EXTENDED LENGTH OF THE STRIP ELEMENT BETWEEN CONNECTIONS TO THE ROOF BARS SUBSTANTIALLY EXCEEDING THE DISTANCE BETWEEN SUCH CONNECTIONS.

\ Filed Jan. 26, 1970 1971 K. M. GROETSCHEL 3,626,700.

SUPERSTRUCTURE IN SELF-ADVANCING ROOF SUPPORTS 2 Sheets-Sheet 1 mvemon.

Karl Mario Groetschel cwa %e ATTORNEYS.

1971 K. M. GROETSCHEL 3,626,700

SUPERSTRUCTURE IN SELF-ADVANCING ROOF SUPPORTS I Filed Jan. 26, 1970 Z ShGBtS-ShGBt 2 [F /A I 27 INVENTOR. Korl Moria GI'OB'ISChGl ATTORNEYS,

United States Patent Oflice 3,626,700 Patented Dec. 14, 1971 3,626,700 SUPERSTRUCTURE IN SELF-ADVANCIN G ROOF SUPPORTS Karl Maria Groetschel, 44 Stolzestrasse, 463 Bochum, Germany Filed Jan. 26, 1970, Ser. No. 5,498 Int. Cl. E21d /44 U.S. Cl. 61-45 D 12 Claims ABSTRACT OF THE DISCLOSURE The invention provides a self-advancing roof support primarily for mine workings in which a roof-engaging superstructure carried by a plurality of hydraulic props upstanding from a base includes laterally spaced, longitudinally extending, roof bars connected with each other by transversely extending spring strip elements incorporating one or more looped, undulating, or arcuate portions to provide an extended length of the strip element between connections to the roof bars substantially exceeding the distance between such connections.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a self-advancing roof support primarily for use in underground mine workings and of the kind comprising a base, a plurality of props thereon, and a roof-engaging superstructure carried by the props. Such supports are hereinafter referred to as being of the kind specified.

The invention is applicable to self-advancing supports of the kind specified both of the one step type and of the two step type. In the former the base comprises a single base element on which all of the props are carried, and in the latter the base comprises more than one base element (usually two), certain of the props being carried on each base element and supporting respective parts of the superstructure, the base elements being advanced at different times when their associated parts of the superstructure are out of load-bearing relation with the roof of the mine working, whilst the parts of the superstructure associated with the remaining base element or elements are maintained by their props in load-bearing relation with the roof. Self-advancement of the support may be effected by any suitable traction means, for example one or more hydraulic rams may be provided on the base to act, in the case of a single base element, between this, and a suitable anchorage, for example a conveyor situated in front of the support and adjacent to the face of the mine working from which coal or other mineral material is to be extracted. Where a plurality of base elements are provided, the ram may be operatively connected between these so as to advance each in turn relatively to the other or others.

It is frequently the case that the downwardly presented surface of the roof to be supported is of irregular, as distinct from planar, form and may present a substantial difference in its height, that is to say the distance between the floor and roof of the mine working within the area to be supported by the superstructure of the support.

Description of the prior art If, as heretofore proposed, the structure is composed of structurally separate elements, such as roof bars extending longitudinally of the support, that is to say in the direction in which the support is adapted to advance, these roof bars being unconnected With each other but supported by respective props, or groups of props, they can readily be raised individually by the desired amount to contact the roof, even though the latter may exhibit substantial differences in height in a direction proceeding from one lateral boundary of the superstructure to the other. In this case, however, it is necessary that the individual roof bars shall provide a substantial depth of interengagement with prop heads by which they are supported in order to ensure that requisite stability of the roof bar against lateral tilting or even against removal from the supporting prop head.

If, on the other hand, also as heretofore proposed, the superstructure comprises laterally spaced, longitudinally extending, roof bars connected substantially rigidly with each other by transversely extending girders form a. frame, the frame may tilt as a whole to accommodate itself to the general plane of the roof, but when the latter presents a severe lateral step, or similar abrupt change in height, there is a possibility of lack of contact, or insuflicient contact, between the roof and one of the longitudinally extending roof bars of the frame leading to insutficient support of this region. Further, the bending stresses produced in the transversely extending girders of the frame may be very high under these conditions, bearing in mind that the supporting prop or props are usually disposed in vertical alignment with the longitudinally extending roof bars of the frame.

The object of the present invention is to provide an improved form of superstructure which is better adapted to meet the particular conditions of operation above referred to than those which have hitherto been available.

SUMMARY OF THE INVENTION According to the invention I provide a roof support of the kind specified wherein the superstructure includes laterally spaced, longitudinally extending, roof bars con nected to each other by one or more transversely extending elastic strip-like elements, each incorporating one or more looped, undulating, or arcuate portions such that the extended length of the element between connections to the roof bars substantially exceeds the distance measured between such connections, the latter being of a form to provid constraint to lateral tilt or bending of each roof bar with respect to the transversely extending element connected thereto.

The preferred form of superstructure is one in which one or each of the transversely extending elements is in the form of a generally oval, elliptical, or other transversely elongated loop arranged vertically, or approximately so, and having a gap or mouth centrally at its upper side. The central portion of the lower side of the element may be of rectilinear form, or may be somewhat concave, that is to say may have its concave side presented upwardly. Preferably, however, the central portion is arched or curved upwardly. This has the advantage of increasing the headroom beneath the transversely extending element and at the same time enables it to act as a support for any further part of the superstructure which may be disposed in the aperture presented between the two laterally spaced roof bars when such further part of the superstructure is lowered by contraction of its supporting prop or props.

The provision of the transversely extending elements allows each of the roof bars to be supported on its associated props by the provision of seatings at the undersides of the roof bars without giving rise to any instability as to the manner in which the roof bars are supported on the associated props, and hence without requiring the provision of any specially designed safety devices to ensure stability. Furthermore, the seatings for the props may be disposed at the undersides of the roof bars, thereby avoid- 3 ing the necessity for forming any openings or sockets within the depth of the roof bars themselves. This enables roof bars of given dimensions and material to present particularly high load-bearing characteristics.

The length of the strip material required to form one or each of the transversely extending strip elements will vary in accordance with the lateral spacing between the roof bars and with the difference in height to which the roof bars are required to be capable of accommodating themselves when in load-bearing relation with the roof. Generally the extended length of one or each of the transversely extending elements may be advantageously selected to be between about two times and about three times the distance between the connections to the roof bars.

The end portions of one or each of the transversely extending elements may be arranged to project in opposite directions (preferably laterally inwardly towards their extremities) in generally parallel or opposed face-to-face relation with the undersides of respective ones of the roof bars, and may be secured thereto by means of respective holders. One form of holder may have a passageway extending transversely of the support for reception of an end portion of an associated one of the transversely extending elements, and releasable means may be provided for retaining such end portion against slidable withdrawal from the passageway lengthwise of the latter.

In an alternative form of holder, this has a recessed seating presented downwardly for the reception of an end portion of an associated one of the transversely extending elements, and a retaining plate is releasably assembled in interlocking relation with the holder beneath such end portion to prevent downward removal thereof from the seating.

With either of these methods of connection, it is a simple matter to effect fitting and removal of the transversely extending elements to and from the roof bars when required. These component parts of the superstructure can, therefore, be individually handled and put in place under operational conditions where the handling of a complete frame-like assembly may present difiiculties.

In a modified form of connection the end portions of the transversely extending elements may extend upwardly to engage in the roof bars and may be fastened thereto adjacent to the extremities of these end portions, the roof bars being provided with abutment means co-operating with the end portions of the transversely extending element at positions spaced downwardly of the fastenings to provide the required constraint against lateral tilt or bending of the roof bars with respect to said element. This arrangement may be adopted advantageously where it is important to save head-room space.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawings wherein:

FIG. 1 is a frontal view of a self-advancing roof support of the kind specified incorporating one embodiment of superstructure in accordance with the invention;

FIG. 2 is a plan view of the outer part of the support illustrated in FIG. 1;

FIG. 3 is a fragmentary cross-sectional view through one of the roof bars of the superstructure illustrating a modified manner of connection between such roof bar and an associated transversely extending element;

FIG. 4 is a view similar to FIG. 3 illustrating a further modified form of connection;

FIG. 5 is a fragmentary view in front elevation illustrating a two part transversely extending element;

FIG. 6 is a fragmentary view in cross-section on the lines 6-6 of FIG. 2 of the embodiment illustrated therein;

FIG. 7 is a view similar to FIG. 6 illustrating a modified form of holder for effecting connection between a roof bar and an associated one of the transversely extending elements in cross-section on the line 7-7 of FIG. 8; and

FIG. 8 is a fragmentary view in side elevation and in cross-section on the line 88 of FIG. 7.

Referring firstly to the embodiment illustrated in FIGS. 1, 2 and 6, the support illustrated is of the two step kind and comprises a base 10 which includes an outer base element 11 formed of two longitudinally extending side members 12 connected at opposite ends to each other by transversely extending members 13, and further comprises an inner base element 14 disposed in, and movable along, the slot or gap defined between the side members 12 of the outer base element.

Traction means in the form of a hydraulic ram (not illustrated) is operatively connected between the inner and outer base elements to advance the former, which is shorter than the latter, along the gap or slot at the required times.

Each of the side members 12 of the outer base element carries longitudinally spaced, upwardly extending, props 15 adjacent to its opposite ends and these, in turn, support roof bars 16 for engaging and supporting the roof 17 of a mine working. The props 15 may be hydraulic props, fluid being supplied from a motor-driven or manually operated pump.

The inner base element 14 also carries longitudinally spaced props such as that seen at 18, which, in turn, carries a central roof bar (shown for convenience only in FIG. 1) which may be equal, or approximately equal, in length to the roof bars 16.

The roof bars 16 are connected with each other at a position adjacent to their rearward ends and at a position vertically, or approximately vertically, above the forward end of the base by transversely extending elements 20.

The elements 20 are formed from resilient strip ma terial, for example spring steel strip, and each of these elements is bent, as viewed in front elevation, to present two approximately semi-circular end portions 21, a central portion 22 integrally connecting the lower ends of the end portions 21. Between the free upper ends of the portions 21 the transversely extending element presents a gap or mouth 24 within which the central roof bar 19 is disposed and through which it can be raised and lowered by means of its supporting props 18, which are similar to the props 15.

The central lower portion 22 of each of the transversely extending elements may be of rectilinear form or bowed downwardly to present a concave upper side, but preferably, as illustrated, it is arched or curved upwardly to present a convex upper side.

The upper limbs of the end portions 21 are connected to respective roof bars 16 medially of the width thereof by means of holders 25 welded or otherwise secured to the undersides of the roof bars.

The latter may be of hollow section and, as illustrated, typically comprise upper and lower horizontal webs connected by a plurality of vertical webs. The disposition of the holders at the undersides of the lower webs avoids the necessity for forming any apertures therein. Likewise, downwardly presented sockets or seatings 15a are secured to the underside of each roof bar to enable same to be supported on its props 15, thereby again avoiding the formation of any apertures. Accordingly the roof bars is able to withstand the full value of longitudinal bending load for which its section is designed by avoidance of points of local weakness.

Each of the holders 25, seen in more detail in FIG. 6, comprises a block of metal welded to the lower web 26 of the associated roof bar 16 and formed with a transversely extending passageway 27 in which an associated end portion 21 is slidably assembled. The tension of the end portion may be effected by any suitable retaining means, for example a bolt 28 screwing into an internally threaded hole in the holder and passing through a clearance hole 29 in the end portion of the transverse element, It will be evident that this method of connection secures the transversely extending element of a cantilever to the underside of the roof bar 16, so that the latter is stabilised against lateral tilting or bending.

If desired vertical clearance may be provided between the upper and lower boundaries of the passageway 27 and the opposed faces of the strip-like transverse element 21 to provide an allowable degree of free tilt before constraint is imposed by virtue of the elasticity of the element itself.

In FIG. 1 there is illustrated a typical roof formation which incorporates a step 30 providing a height difference in the left and right-hand portions of the roof with respect to the floor 31 of the mine working. A step of the magnitude illustrated cannot readily allow a rigid frame to accommodate itself to the general plane of the roof and at the same time afford satisfactory support thereto, whereas when the outer part of the superstructure is constructed as above described, such confirmation is possible and satisfactory support can be furnished. Thus, as illustrated in chain lines, it will be noted that the right-hand one of the roof bars 16 is in full engagement with the portion of the roof to the right-hand side of the step 30 as is also the left-hand roof bar with respect to its portion of the roof. Deflection of the transversely extending strip-like element 20 is illustrated in chain lines and is readily accommodated without any high local stressing of this element due to the incorporation of the loop-like end portions 21 which, by their presence, result in the existence of a length of strip material in the transversely extending element substantially exceeding the distance between the connections to the roof bars (measured at the centre points of the holders 25).

A modified form of holder may be employed, if desired, and is illustrated in FIG. 7 wherein the parts corresponding to those already described are designated by like numerals of rererence with the prefix 1, the preceding description being applicable.

In this case each holder 125 is of channel shape and includes downwardly extending flanges 125a and 125b at opposite ends, these flanges and the intervening top portion of the holder thus defining a downwardly presented recessed seating in which the end portion 121 of the associated transversely extending element is received.

This end portion is retained in position by a wedge member 128 passing through apertures in the flanges 125a, 1251: so as to be interlocked with the holder beneath the end portion 121.

The wedge element can be driven into position by hammer blows on the right-hand end as viewed in FIG.

8, and similarly can be released by hammer blows on the left-hand end. I

The central portion 22 of each transversely extending element may act as a support for the central roof bar 19 when the latter is lowered, and, if desired, vertically extending slide or guide parts may be provided either on each of the transversely extending elements or on the roof bars 16 to prevent inadvertent lateral displacement of the central roof bar into the openings presented by the looplike end portions 21.

A modified connection arrangement is illustrated in FIG. 3 wherein parts corresponding to those already described are designated by like numerals of reference with the prefix 2 and to which the preceding description is to be deemed to apply.

In this case a holder 225 is secured to the underside of the top web of the roof bar 216 and the end portion 221 of the associated transversely extending element enters through an aperture 216a in one of the vertical webs of the roof bar. Access to the securing bolt 228 is by way of an aperture 21Gb.

A further modified form of connection is illustrated in FIG. 4 where parts corresponding to those already described are designated by like numerals of reference with the prefix 3 and to which the preceding description is to be deemed to apply.

In this case the end portions 321 of each transversely extending element project upwardly and are secured to the associated roof bar 316 by a fastening comprising a pair of lugs 316a welded or otherwise secured internally of the roof bar to the top web thereof and a removable pin 31Gb passing through the lugs and through the end portion -321.

To the lower web of the roof bar are secured plates 3160 which provide a gap through which the end portion 321 of the transversely extending element can enter, either as a sliding fit or with some predetermined clearance. The plates 316a act as stop or abutment elements and, in combination with the fastening 316a, 316b, provide the required constraint to tilting or lateral bending of the roof bar.

A further modification illustrated in FIG. 4 is that the transversely extending element includes an upwardly arched portion 320a immediately inwardly of the looped portion 321. By this arrangement the requisite length of strip material is incorporated in the transversely extending element, notwithstanding the intrinsic shortening thereof arising through entry upwardly into the interior of the roof bar instead of approach to the roof bar from the lateral outer side, as in the arrangement illustrated in. FIG. 1 or FIG. 3. The upwardly arched portion 320a can also act to prevent inadvertent lateral displacement of the central roof bar when resting on the central portion of the transversely extending element.

A further modification is illustrated in FIG. 5 wherein parts corresponding to those already described are designated by like numerals of reference with the prefix 4 and to which the preceding description is to be deemed to apply.

In this case each transversely extending element is formed of two component parts joined centrally. The lower limbs 422a of each component are overlapped with each other and are enclosed by a sleeve 42212. A fastening element such as a bolt 422a extend through the sleeve and through the overlapping end portions of the limbs 422a, one at least of which has a longitudinally extending slot to permit of adjustment in the direction of the length of these limbs, after which the bolt can be tightened to secure the components in any adjusted position within the range of travel.

In all of the foregoing embodiments the length of strip material in each transversely extending element is made greater than the distance between the connections to the roof bars by an amount such as to allow relative vertical movement of the roof bars by a distance which may be as much as one quarter to one third the overall width of the superstructure without any local high stressing of the strip material. In general this condition can be achieved by making the length of strip material two to three times longer than the distance between the connections, but supports intended for use in less severe or more severe conditions than are normally encountered as regards roof irregularity may use lesser or greater lengths of strip material.

It will be noted that in the particular embodiment shown in FIGS. 1, 2 and 6 the length of strip material in each element 22 is about 2 /2 times the distance between centres of the holders 25, and this easily enables the superstructure to accommodate a roof height diflerence of the order of /s of the overall width of the super structure without any part of each element 20 being subjected to severe local deflection and hence bending stress. If desired any of the roof bars, such as 16 or 19, may incorporate a joint at a selected position along its length, for example about midway, providing for some degree of articulation about a transverse horizontal axis between the components of such roof bar, either with or without spring constraint with respect to a median position in which the components are colinear.

I claim:

1. A self-advancing roof support comprising a base, a plurality of props thereon, a roof-engaging superstructure carried by the props, and means for advancing the support, including the improvement wherein:

(a) the superstructure comprises a plurality of (i) roof bars extending longitudinally of the support and spaced apart transversely thereof,

(ii) one or more connecting elements extending transversely of the support between said roof bars and terminating in end portions,

(iii) connection means connecting said end portions with said roof bars and constraining said roof bars against lateral tilt with respect I) said end portions,

(b) each of said connecting elements is formed of elastic strip material,

(c) each of said connecting elements incorporates at least one generally U-shaped portion lying in a sub stantially vertical plane and each of said connecting elements incorporates a length of said strip material substantially exceeding the distance between said connection means connecting said element with said roof bars.

2. A support according to claim 1 wherein each of said connecting elements includes two of said Ushaped portions at opposite ends of the connecting element arranged With their open ends presented laterally inwardly to define a substantially vertical transversely elongated loop having a gap or mouth centrally at its upper side.

3. A support according to claim 2 wherein each of said connecting elements incorporates a central portion at its lower side which is arched or curved upwardly.

4. A support according to claim 1 wherein each of said connecting elements has an extended length of strip material incorporated therein of between about two times and about three times the distance between said connection means connecting said element to said roof bars.

5. A support according to claim 1 wherein:

(a) said end portions are assembled in generally parallel face-to-face relation with respective ones of said roof bars and disposed adjacent to the undersides of said roof bars,

(b) said connection means each comprises a holder secured to the underside of an associated one of said roof bars,

() said end portions of each of said connecting elements are secured releasably to respective ones of said holders by releasable retaining means.

6. A support according to claim 5 wherein:

(a) each of said holders includes a block-like body having a passageway extending transversely therethrough for the reception of an associated one of said end portions,

(b) said releasable retaining means co-operates with the end portion received in said passageway to retain same against withdrawal from said passageway longitudinally thereof.

7. A support according to claim 5 wherein:

(a) each of said holders has a body defining a downwardly presented recessed seating for the reception of a respective one of said end portions,

(b) said retaining means comprises a retaining plate releasably interlocked with said body and disposed in said seating beneath said end portion to prevent downward removal of said end portion from said seating.

8. A support according to claim 1 wherein:

(a) each of said end portions extend upwardly towards their terminations,

(b) said upwardly extending end portions engage in respective ones of said roof bars,

(0) said connection means includes fastening means for connecting extremities of said end portions to said roof bars in the interiors of the latter,

((1) said connection means includes abutment means adjacent to the underside of said roof bars and c0- operating with said end portions at a position downwardly of said fastening means to constrain said roof bars against lateral tilt or bending with respect to each of said connecting elements.

9. A roof support according to claim 1 wherein:

(a) each of said connecting elements comprises structurally separate components,

(b) said components include limb portions extending from outer end portions of said components in a direction transversely inwardly of said support and into overlapping relation with each other,

(0) securing means are provided in assembied relation with said overlapping parts to secure same together.

10. A support according to claim 9 wherein said overlapping parts are movable relatively to each other in a direction transversely of said support to adjust the distance between the end portions in accordance with the lateral displacing of the roof bars connected thereby, and stop means are provided to limit the extent of said relative movement.

11. A support according to claim 2 wherein each of said U-shaped portions is of at least approximately partcircular form and is connected integrally at its upper side to one of said end portions, the latter projecting inwardly in a direction transversely of said support.

12. A support according to claim 1 wherein said superstructure includes a further roof bar extending longitudinally of said support and situated between said laterally spaced roof bars, said base includes an outer base element having laterally spaced side members connected to each other at opposite ends to define a slot or gap, and includes a relatively longitudinally movable inner base element disposed in said gap, said transversely spaced roof bars and connecting elements being carried by one of said props on said outer base element spaced apart along each of said side members thereof, and said further roof bar being carried by at least one of said props on said inner base element.

References Cited UNITED STATES PATENTS 3,192,722 7/1965 Herrmann et al 6l-45 D 3,295,331 l/1967 Blaser et al 6i45 D FOREIGN PATENTS 858,633 1/1961 Great Britain 6l--45 D 942,310 11/1963 Great Britain 6145 D 1,058,019 2/1967 Great Britain 61-45 D 1,249,554 11/1960 France 6145 D 1,368,750 6/1964 France 6145 D DENNIS L. TAYLOR, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTlON Patent No. 3 626 700 Dated December 14th 1971 lnventofls) Karl Maria Groetschel It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column. 1, after line 6, insert -Claims priority, application Germany, Jan. 27, 1969, P 19 03 890.5. Column 2, line 44, change "provid" to provide. Column 4, line 75, change "of" to as. Column 5, line 35, correct the spelling of "reference".

Signed and sealed this 8th day ofAugust 1972.

(SEAL) Attest:

EDWARD M.FI. ETCHE1R,JR. ROBERT GOTTSGHALK ttesting Officer Commissioner of Patents FORM PO-1050 (10-69) USCOMM-DC 60375-P69 9 UTS. GOVERNMENT PRINTING OFFICE: l969 0-365-33A 

